1 /* $NetBSD: roken_gethostby.c,v 1.2 2017/01/28 21:31:50 christos Exp $ */
2
3 /*
4 * Copyright (c) 1998 Kungliga Tekniska Högskolan
5 * (Royal Institute of Technology, Stockholm, Sweden).
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * 3. Neither the name of the Institute nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36 #include <config.h>
37
38 #include <krb5/roken.h>
39
40 #undef roken_gethostbyname
41 #undef roken_gethostbyaddr
42
43 static struct sockaddr_in dns_addr;
44 static char *dns_req;
45
46 static int
make_address(const char * address,struct in_addr * ip)47 make_address(const char *address, struct in_addr *ip)
48 {
49 if(inet_aton(address, ip) == 0){
50 /* try to resolve as hostname, it might work if the address we
51 are trying to lookup is local, for instance a web proxy */
52 struct hostent *he = gethostbyname(address);
53 if(he) {
54 unsigned char *p = (unsigned char*)he->h_addr;
55 ip->s_addr = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
56 } else {
57 return -1;
58 }
59 }
60 return 0;
61 }
62
63 static int
setup_int(const char * proxy_host,short proxy_port,const char * dns_host,short dns_port,const char * dns_path)64 setup_int(const char *proxy_host, short proxy_port,
65 const char *dns_host, short dns_port,
66 const char *dns_path)
67 {
68 memset(&dns_addr, 0, sizeof(dns_addr));
69 if(dns_req)
70 free(dns_req);
71 dns_req = NULL;
72 if(proxy_host) {
73 if(make_address(proxy_host, &dns_addr.sin_addr) != 0)
74 return -1;
75 dns_addr.sin_port = htons(proxy_port);
76 if (asprintf(&dns_req, "http://%s:%d%s", dns_host, dns_port, dns_path) < 0)
77 return -1;
78 } else {
79 if(make_address(dns_host, &dns_addr.sin_addr) != 0)
80 return -1;
81 dns_addr.sin_port = htons(dns_port);
82 if (asprintf(&dns_req, "%s", dns_path) < 0)
83 return -1;
84 }
85 dns_addr.sin_family = AF_INET;
86 return 0;
87 }
88
89 static void
split_spec(const char * spec,char ** host,int * port,char ** path,int def_port)90 split_spec(const char *spec, char **host, int *port, char **path, int def_port)
91 {
92 char *p;
93 *host = strdup(spec);
94 p = strchr(*host, ':');
95 if(p) {
96 *p++ = '\0';
97 if(sscanf(p, "%d", port) != 1)
98 *port = def_port;
99 } else
100 *port = def_port;
101 p = strchr(p ? p : *host, '/');
102 if(p) {
103 if(path)
104 *path = strdup(p);
105 *p = '\0';
106 }else
107 if(path)
108 *path = NULL;
109 }
110
111
112 ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL
roken_gethostby_setup(const char * proxy_spec,const char * dns_spec)113 roken_gethostby_setup(const char *proxy_spec, const char *dns_spec)
114 {
115 char *proxy_host = NULL;
116 int proxy_port = 0;
117 char *dns_host, *dns_path;
118 int dns_port;
119
120 int ret = -1;
121
122 split_spec(dns_spec, &dns_host, &dns_port, &dns_path, 80);
123 if(dns_path == NULL)
124 goto out;
125 if(proxy_spec)
126 split_spec(proxy_spec, &proxy_host, &proxy_port, NULL, 80);
127 ret = setup_int(proxy_host, proxy_port, dns_host, dns_port, dns_path);
128 out:
129 free(proxy_host);
130 free(dns_host);
131 free(dns_path);
132 return ret;
133 }
134
135
136 /* Try to lookup a name or an ip-address using http as transport
137 mechanism. See the end of this file for an example program. */
138 static struct hostent*
roken_gethostby(const char * hostname)139 roken_gethostby(const char *hostname)
140 {
141 int s;
142 struct sockaddr_in addr;
143 char *request = NULL;
144 char buf[1024];
145 int offset = 0;
146 int n;
147 char *p, *foo;
148 size_t len;
149
150 if(dns_addr.sin_family == 0)
151 return NULL; /* no configured host */
152 addr = dns_addr;
153 if (asprintf(&request, "GET %s?%s HTTP/1.0\r\n\r\n", dns_req, hostname) < 0)
154 return NULL;
155 if(request == NULL)
156 return NULL;
157 s = socket(AF_INET, SOCK_STREAM, 0);
158 if(s < 0) {
159 free(request);
160 return NULL;
161 }
162 if(connect(s, (struct sockaddr*)&addr, sizeof(addr)) < 0) {
163 close(s);
164 free(request);
165 return NULL;
166 }
167
168 len = strlen(request);
169 if(write(s, request, len) != (ssize_t)len) {
170 close(s);
171 free(request);
172 return NULL;
173 }
174 free(request);
175 while(1) {
176 n = read(s, buf + offset, sizeof(buf) - offset);
177 if(n <= 0)
178 break;
179 offset += n;
180 }
181 buf[offset] = '\0';
182 close(s);
183 p = strstr(buf, "\r\n\r\n"); /* find end of header */
184 if(p) p += 4;
185 else return NULL;
186 foo = NULL;
187 p = strtok_r(p, " \t\r\n", &foo);
188 if(p == NULL)
189 return NULL;
190 {
191 /* make a hostent to return */
192 #define MAX_ADDRS 16
193 static struct hostent he;
194 static char addrs[4 * MAX_ADDRS];
195 static char *addr_list[MAX_ADDRS + 1];
196 int num_addrs = 0;
197
198 he.h_name = p;
199 he.h_aliases = NULL;
200 he.h_addrtype = AF_INET;
201 he.h_length = 4;
202
203 while((p = strtok_r(NULL, " \t\r\n", &foo)) && num_addrs < MAX_ADDRS) {
204 struct in_addr ip;
205 inet_aton(p, &ip);
206 ip.s_addr = ntohl(ip.s_addr);
207 addr_list[num_addrs] = &addrs[num_addrs * 4];
208 addrs[num_addrs * 4 + 0] = (ip.s_addr >> 24) & 0xff;
209 addrs[num_addrs * 4 + 1] = (ip.s_addr >> 16) & 0xff;
210 addrs[num_addrs * 4 + 2] = (ip.s_addr >> 8) & 0xff;
211 addrs[num_addrs * 4 + 3] = (ip.s_addr >> 0) & 0xff;
212 addr_list[++num_addrs] = NULL;
213 }
214 he.h_addr_list = addr_list;
215 return &he;
216 }
217 }
218
219 ROKEN_LIB_FUNCTION struct hostent* ROKEN_LIB_CALL
roken_gethostbyname(const char * hostname)220 roken_gethostbyname(const char *hostname)
221 {
222 struct hostent *he;
223 he = gethostbyname(hostname);
224 if(he)
225 return he;
226 return roken_gethostby(hostname);
227 }
228
229 ROKEN_LIB_FUNCTION struct hostent* ROKEN_LIB_CALL
roken_gethostbyaddr(const void * addr,size_t len,int type)230 roken_gethostbyaddr(const void *addr, size_t len, int type)
231 {
232 struct in_addr a;
233 const char *p;
234 struct hostent *he;
235 he = gethostbyaddr(addr, len, type);
236 if(he)
237 return he;
238 if(type != AF_INET || len != 4)
239 return NULL;
240 p = addr;
241 a.s_addr = htonl((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]);
242 return roken_gethostby(inet_ntoa(a));
243 }
244
245 #if 0
246
247 /* this program can be used as a cgi `script' to lookup names and
248 ip-addresses */
249
250 #include <stdio.h>
251 #include <stdlib.h>
252 #include <netdb.h>
253 #include <sys/param.h>
254
255 int
256 main(int argc, char **argv)
257 {
258 char *query = getenv("QUERY_STRING");
259 char host[MAXHOSTNAMELEN];
260 int i;
261 struct hostent *he;
262
263 printf("Content-type: text/plain\n\n");
264 if(query == NULL)
265 exit(0);
266 he = gethostbyname(query);
267 strncpy(host, he->h_name, sizeof(host));
268 host[sizeof(host) - 1] = '\0';
269 he = gethostbyaddr(he->h_addr, he->h_length, AF_INET);
270 printf("%s\n", he->h_name);
271 for(i = 0; he->h_addr_list[i]; i++) {
272 struct in_addr ip;
273 unsigned char *p = (unsigned char*)he->h_addr_list[i];
274 ip.s_addr = htonl((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]);
275 printf("%s\n", inet_ntoa(ip));
276 }
277 exit(0);
278 }
279
280 #endif
281